Vinyl chloride resin fiber and method for producing same

ABSTRACT

To provide a fiber made of a vinyl chloride resin which is excellent in heat resistance and thus hardly shrinks thermally even at a temperature exceeding 100° C. 
     The fiber obtained by melt-spinning a resin composition comprising a vinyl chloride resin and from 1 to 300 parts by mass of a polyester resin based on 100 parts by mass of the vinyl chloride resin, wherein the vinyl chloride resin has a viscosity average polymerization degree of from 600 to 2,500; the polyester resin is a polylactic acid type resin; and the polyester resin has the melting point of from 100 to 300° C.

TECHNICAL FIELD

The present invention relates to a vinyl chloride resin fiber which is excellent in heat resistance and thus hardly shrinks thermally, and to a process for producing it.

BACKGROUND ART

Heretofore, a vinyl chloride resin has been used for various applications as a typical plastic for general purposes, since it is excellent in weather resistance, transparency, flame retardance or chemical resistance and is inexpensive. The fiber has a strength, degree of elongation, texture, etc. similar to natural hair, whereby it is commonly used as a fiber for artificial hair such as a hair wig or doll hair.

However, in order to make it more similar to natural hair, various secondary processing of the fiber is carried out. However, as a result, in the processing step for a hair wig, there is a problem such that the fiber shrinks thermally more than necessary. As a method to overcome such a problem, it is suggested to use a vinyl chloride fiber made of a vinyl chloride resin and a chlorinated vinyl chloride resin (Patent Document 1). However, in such a method, it is difficult to add a large amount of the chlorinated vinyl chloride resin, and a sufficient effect was not sometimes obtained.

Further, it is suggested to use a vinyl chloride fiber wherein 2 types of specific chlorinated vinyl chloride resins are added (Patent Document 2). By such a method, it was possible to increase the amount of the chlorinated vinyl chloride resin to be added, and it was possible to prevent thermal shrinkage around 100° C. However, in recent years, since styles of wigs for head decoration became diversified and sophisticated, a processing treatment is required to be carried out at a higher temperature, which was difficult to fulfill with the above method, and the fiber was sometimes poor in is processing characteristics.

Patent Document 1: JP-B-60-18323

Patent Document 2: JP-A-2003-193329

DISCLOSURE OF THE INVENTION Object to be Accomplished by the Invention

The object of the present invention is to provide a fiber made of a vinyl chloride resin which is excellent in heat resistance and thus hardly shrinks thermally even at a temperature exceeding 100° C., and to provide a process for producing it.

Means to Accomplish the Object

Namely, the present invention provides the following.

(1) A vinyl chloride resin fiber made of a melt-spun fiber of a resin composition comprising a vinyl chloride resin and a polyester resin in an amount of from 1 to 300 parts by mass, based on 100 parts by mass of the vinyl chloride resin. (2) The vinyl chloride resin fiber according to the above (1), wherein the vinyl chloride resin has a viscosity average polymerization degree of from 600 to 2,500. (3) The vinyl chloride resin fiber according to the above (1) or (2), wherein the polyester resin has a melting point of from 100 to 300° C. (4) The vinyl chloride resin fiber according to any one of the above (1) to (3), wherein the polyester resin is a polylactic acid type resin. (5) The vinyl chloride resin fiber according to any one of the above (1) to (4), which has a fineness of monofilament of from 1 to 200 decitex. (6) Artificial hair made of the vinyl chloride resin fiber as defined in any one of the above (1) to (5). (7) A process for producing a vinyl chloride resin fiber sequentially comprising:

(a) a step of mixing a resin composition comprising a vinyl chloride resin and a polyester resin;

(b) a step of melt-spinning the above resin composition from a spinneret at a resin temperature of from 150 to 200° C.;

(c) a step of stretching the above melt-spun fiber in an atmosphere of air held at a temperature of from 30 to 150° C. to have a stretching ratio of from 2 to 20 times as much;

(d) a step of subjecting the above stretched fiber to thermal relaxing treatment in an atmosphere of air held at a temperature of from 80 to 200° C. until the entire length of the fiber becomes from 99.8 to 50% of the length before the treatment.

(8) The process for producing a vinyl chloride resin fiber according to the above (7), wherein the sectional area per nozzle hole used in the above step of melt-spinning is at most 3 mm².

EFFECT OF THE INVENTION

According to the present invention, it is possible to provide a fiber made of a vinyl chloride resin which is excellent in heat resistance and thus hardly shrinks thermally even at a temperature exceeding 100° C., has a little gloss and is suitable as a fiber for hair decoration or artificial hair; and to provide a process for producing it.

BEST MODE FOR CARRYING OUT THE INVENTION

The fiber made of a vinyl chloride resin of the present invention is formed by a resin composition comprising a vinyl chloride resin and from 1 to 300 parts by mass of a polyester resin, based on 100 parts by mass of the vinyl chloride resin.

As the vinyl chloride resin used in the present invention, it is possible to use a resin obtained by e.g. bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization. However, in consideration of e.g. the initial coloration of fibers, it is preferred to use one prepared by suspension polymerization.

The vinyl chloride resin may be a homopolymer resin which is a conventional homopolymer of vinyl chloride or various types of conventional vinyl chloride copolymer resins and is not particularly limited.

As such a vinyl chloride copolymer resin, it is possible to use a conventional copolymer resin. It may, for example, be a copolymer resin of vinyl chloride with a vinyl ester, such as a vinyl chloride/vinyl acetate copolymer resin or a vinyl chloride/vinyl propionate copolymer resin; a copolymer resin of vinyl chloride with an acrylate, such as a vinyl chloride/butyl acrylate copolymer resin or a vinyl chloride/2-ethylhexyl acrylate copolymer resin; a copolymer resin of vinyl chloride with an olefin such as a vinyl chloride/ethylene copolymer resin or a vinyl chloride/propylene copolymer resin; and a vinyl chloride/acrylonitrile copolymer resin. It is particularly preferred to use a homopolymer resin which is a homopolymer of vinyl chloride, or a vinyl chloride/ethlene copolymer resin or a vinyl chloride/vinyl acetate copolymer resin.

In such a vinyl copolymer resin, the content of the comonomer is not particularly limited and may be determined depending upon the required product quality such as the molding processability, fiber properties, etc. The content of the comonomer is preferably from 2 to 30 mass %, particularly preferably from 2 to 20 mass %.

The viscosity average polymerization degree of the vinyl chloride resin to be used in the present invention is preferably from 600 to 2,500, more preferably from 600 to 1,800. If it is less than 600, the melt viscosity tends to be low, and the obtained fibers tend to be susceptible to thermal shrinkage. On the other hand, if the viscosity average polymerization degree exceeds 2,500, the melt viscosity tends to be high, and the nozzle pressure tends to be high, whereby a safe production will sometimes be difficult. Here, the viscosity average polymerization degree is a value calculated by JIS K6720-2 by dissolving 200 mg of the resin in 50 ml of nitrobenzene and measuring the specific viscosity of this polymer solution in a constant temperature tank of 30° C. by using a Ubbelohde viscometer.

The polyester resin to be used in the present invention may, for example, be an aromatic polyester resin such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate; or an aliphatic polyester resin such as polylactic acid, polyhydroxy butanoic acid, polycaprolactone, polybutylene succinate, polybutylene adipate, polyethylene succinate, polyglycolic acid, poly-3-hydroxypropionate or poly-3-hydroxybutylate.

Further, the above polyester resin includes a copolymer of such a polyester resin, a block or a graft polymer of such a polyester resin and a blended product with other resins. It is not particularly limited, but from the viewpoint of mixing property with a vinyl chloride resin, it is preferably an aliphatic polyester resin, particularly preferably a polylactic acid resin.

The melting point of the polyester resin of the present invention is preferably from 100 to 300° C., particularly preferably from 120 to 250° C., most preferably from 130 to 200° C. It is preferred to use one having crystallinity. If the melting point of the polyester resin is less than 100° C., heat resistance of fiber to be obtained therefrom will sometimes be poor. On the other hand, if the melting point exceeds 300° C., it will sometimes be difficult to mix it with the vinyl chloride resin.

The above melting point of the polyester resin represents a temperature at the peak of a calorie for melting when by using a Differential Scanning Calorimetry (DSC), 5 mg of a sample was heated at a temperature raising rate of 10° C./minute in nitrogen and is a value calculated in accordance with JISK-7121.

The preferred polylactic acid resin of the present invention is not particularly limited.

Generally it is known that when the optical purity of the polylactic acid is low, the crystallinity will decrease, particularly, the melting point will decrease. Therefore, one having L form at least 70%, preferably at least 80%, particularly preferably at least 90%, is used.

The molecular weight of the polylactic acid resin to be used in the present invention is, as a weight-average molecular weight as calculated as standard polystyrene measured by gel permeation chromatography, preferably from 10,000 to 1,000,000, more preferably from 20,000 to 750,000, particularly preferably from 30,000 to 500,000. If the weight-average molecular weight is small, the effect for improving the heat resistance of fiber to be obtained will be poor, and if it is large, the mixing with the vinyl chloride resin will sometimes be difficult.

The resin composition constituting the fiber of the present invention is one comprising a vinyl chloride resin and a polyester resin in an amount of from 1 to 300 parts by mass, preferably from 2 to 200 parts by mass, particularly preferably from 5 to 150 parts by mass, most preferably from 10 to 100 parts by mass, based on 100 parts by mass of the vinyl chloride resin. If the polyester resin is less than 1 part by mass, the heat resistance of fiber to be obtained will deteriorate. On the other hand, if the polyester resin exceeds 300 parts by mass, the flame retardancy of fiber to be obtained will deteriorate.

In the resin composition for constituting the fiber of the present invention, in addition to the vinyl chloride and the polyester resin, it is possible to mix conventional additives to be used for the vinyl chloride resin, as the case requires. Such additives are not particularly limited, and known additives may be incorporated depending upon the particular purpose. They may, for example, be a lubricant, a heat stabilizer, a processing auxiliary, a reinforcing agent, an ultraviolet absorber, an antioxidant, an antistatic agent, a filler, a flame retardant, a pigment, an initial coloration-improving agent, a conductivity-imparting agent, a surface treating agent, a light stabilizer and a perfume.

Now, the process for producing the vinyl chloride resin fiber of the present invention will be described.

The resin composition comprising the vinyl chloride and the polyester resin, and additives as the case requires, to be used for producing the fiber of the present invention, may be used in the form of a powder compound obtained by mixing by using a conventional mixing machine, for example, a Henschel mixer, a super mixer or a ribbon blender, or in the form of a pellet compound obtained by melting and mixing the powder compound.

The powder compound can be usually produced under conventional conditions. Further, the pellet compound can be prepared in the same manner as the preparation of a usual vinyl chloride type pellet compound. For example, the pellet compound may be prepared by using a kneader such as a single screw extruder, a counter-rotating twin screw extruder, a conical twin screw extruder, a co-rotating twin screw extruder, a co-kneader, a planetary gear extruder or a roll kneader.

In the present invention, the above resin composition is formed into a non-stretched fiber by a conventional spinning method. The spinning method is not particularly limited, but a melt spinning method is preferred. A conventional extruder can be used when melt-spinning is carried out. For example, it is possible to use a single screw extruder, a counter-rotating twin screw extruder, a conical twin screw extruder, etc., but it is particularly preferred to use a single screw extruder having an aperture of approximately from 35 to 200 mm or a conical twin screw extruder having an aperture of approximately from 35 to 150 mm.

In the present invention, it is possible to carry out the melt-spinning by using conventional nozzles. For example, it is preferred to carry out melt-spinning by providing nozzles having a sectional area per nozzle hole, of at most 3 mm², more preferably at most 1 mm², particularly preferably at most 0.5 mm², at the forward end of a die (spinneret). If the sectional area per nozzle hole exceeds 3 mm², it will be required to exert an excessive tension to form a fine non-stretched fiber or stretched fiber, whereby the fiber sometimes breaks. The shape of a sectional area of a nozzle hole is preferably a circular hollow-shape, a spectacled-shape, a Y-shape or a C-shape.

In the present invention, it is preferred to produce non-stretched fibers preferably having a fineness of monofilament of at most 300 decitex by extruding strands from multi-type nozzles having a plurality of nozzle holes having a sectional area of at most 3 mm² per nozzle hole, arranged in a die (the number of nozzle holes is preferably from 50 to 500, the number of rows of nozzles is preferably from 1 to 5 rows).

Specifically, it is possible to obtain a non-stretched fiber, for example, by melt-spinning the resin composition such as a pellet compound at a resin temperature of preferably from 150 to 200° C., more preferably from 155 to 195° C., by using a single screw extruder.

By subjecting the non-stretched fiber obtained by the above melt-spinning to stretch treatment or thermal treatment by a conventional method, it is possible to obtain a fine fiber (stretched fiber) of preferably at most 600 decitex. With respect to the stretching conditions, the stretching is carried out preferably in an atmosphere of air held at a stretch treating temperature of preferably from 30 to 150° C. at a stretching ratio of preferably from 2 to 20 times as much. Particularly, the stretching is carried out in an atmosphere of air at a stretch treating temperature of preferably from 80 to 140° C. at a stretching ratio of preferably from 2 to 10 times as much.

Further, it is possible to decrease the degree of thermal shrinkage, by subjecting the stretched fiber to thermal relaxing treatment in an atmosphere of air held at a temperature of from 80 to 200° C. until the entire length of the fiber becomes preferably from 99.8 to 50%, more preferably from 99.8 to 70%, of the length before the treatment. The thermal relaxing treatment can be carried out in combination with or independently from the stretching treatment.

Further, in the present invention, it is possible to apply conventional techniques of melt spinning e.g. a technique relating to sectional shapes of various nozzles, a technique relating to a heating tube and a technique relating to thermal treatment, in optional combination.

With respect to the fiber obtained by subjecting a non-stretched fiber to stretching treatment and thermal treatment, the fineness of its monofilament is preferably from 1 to 200 decitex, more preferably from 5 to 150 decitex, particularly preferably from 10 to 100 decitex. Here, if the fiber is thin or thick, it is isolated from a natural product, and its natural appearance is deteriorated.

Decitex is a value wherein weights of 20 fibers each having a length of 100 cm were measured, and an average weight per fiber is multiplied by 10,000.

In the present invention, although it is not so limited, the fineness of monofilament of the above fiber is not necessarily uniform, and as the case requires, it is possible to use multiple fibers different in fineness of monofilament, as blended, in a step of spinning or after spinning.

EXAMPLES

Now, the present invention will be described in further detail with reference to Examples, but it should be understood that the present invention is by no means restricted by such Examples.

Example 1

(a) A fiber having a fineness of monofilament of 65 decitex was obtained by sequentially carrying out (a) a step of obtaining a resin composition by stirring and heating up to 100° C. by a Henschel mixer, a resin composition comprising 100 parts by mass of a vinyl chloride copolymer resin (manufactured by Taiyo Vinyl Corp., TH-1000; viscosity average polymerization degree: 1,000), 50 parts by mass of a polylactic acid type resin (manufactured by UNITIKA. LTD., Terramac TE-4000, melting point: 170° C.), 1 part by mass of a hydrotalcite type composite thermal stabilizer (manufactured by Nissan Chemical Industries, Ltd., CP-410A) and 0.75 part by mass of an ester lubricant (RIKEN VITAMIN Co., LTD., EW-100), (b) a step of obtaining non-stretched fibers having an average fineness of 150 decitex by melt-spinning the above resin composition at a spinneret temperature of 190° C. at an extrusion rate of 15 kg/hr by using a 40 mm single screw extruder controlled at 175 to 185° C., and by using a spinneret having circular nozzles, a sectional area per nozzle of 0.05 mm² and 180 nozzle holes, (c) a step of stretching the above melt-spun fibers 300% in an atmosphere of air at 105° C., and (d) a step of applying thermal relaxing treatment in an atmosphere of air at 140° C. until the entire length of fibers shrunk to a length of 75% of the length before the treatment.

Examples 2 to 10

The fiber was obtained in the same manner as in Example 1 by using the vinyl chloride resin and the polyester resin in blending amounts as shown in Table 1.

Example 11

The fiber was obtained in the same manner as in Example 1, except that the vinyl chloride resin was changed to a vinyl chloride resin having a low polymerization degree (manufactured by Taiyo Vinyl Corp., TH-700, viscosity average polymerization degree: 700).

Example 12

The fiber was obtained in the same manner as in Example 1, except that the vinyl chloride resin was changed to a vinyl chloride resin having a high polymerization degree (manufactured by Taiyo Vinyl Corp., TH-2000, viscosity average polymerization degree: 2,000).

Example 13

The fiber was obtained in the same manner as in Example 1, except that the vinyl chloride resin was changed to a vinyl chloride/ethylene copolymer resin (manufactured by Taiyo Vinyl Corp., TE-1050, content of vinyl chloride: 98 mass %, viscosity average polymerization degree: 1,050).

Example 14

The fiber was obtained in the same manner as in Example 1, except that the vinyl chloride resin was changed to a vinyl chloride/vinyl acetate copolymer resin (manufactured by Taiyo Vinyl Corp., TV-800, content of vinyl chloride: 93 mass %, viscosity average polymerization degree: 780).

Example 15

The fiber was obtained in the same manner as in Example 1, except that the polylactic acid type resin was changed to a polyester resin having crystallinity (manufactured by TOYOBO Co., LTD., VYLON GM-925, melting point: 166° C.)

Example 16

The fiber was obtained in the same manner as in Example 1, except that the polylactic acid resin was changed to a polyester resin having crystallinity (manufactured by TOYOBO Co., LTD., VYLON GA-5410, melting point: 117° C.)

Comparative Example 1

The fiber was obtained in the same manner as in Example 1, except that the polylactic acid type resin was not contained.

Comparative Examples 2 and 3

The fiber was obtained in the same manner as in Example 1 by using a chlorinated vinyl chloride resin (manufactured by SEKISUI CHEMICAL Co., LTD., HA-24K) in a blending amount shown in Table 2, instead of the polylactic acid type resin.

The results of the above Examples 1 to 16 and Comparative Examples 1 to 3 are shown in Tables 1 and 2, respectively.

TABLE 1 Examples 1 2 3 4 5 6 7 8 Blend Vinyl TH-1000 100  100 100  100 100  100 100  100  chloride (Parts) resin TH-700 — — — — — — — — (Parts) TH-2000 — — — — — — — — (Parts) TE-1050 — — — — — — — — (Parts) TV-800 — — — — — — — — (Parts) Poly- TE-4000 50 100 10 200 5 270  1 2 ester (Parts) GM-925 — — — — — — — — (Parts) GA-5410 — — — — — — — — (Parts) Characteristics Fineness of 65  63 66  61 67   60 61 60  monofilament Spinning property  0  0  0  1 0  2  0 0 (number of times) Thermal shrinkage (%)  3  2  5  1 7  1 10 8 Gloss Good Good Excellent Fair Excellent Fair Fair Good Examples 9 10 11 12 13 14 15 16 Blend Vinyl TH-1000 100 100 — — — — 100  100  chloride (Parts) resin TH-700 — — 100  — — — — — (Parts) TH-2000 — — — 100  — — — — (Parts) TE-1050 — — — — 100  — — — (Parts) TV-800 — — — — — 100  — — (Parts) Poly- TE-4000 150 300 50 50 50 50 — — ester (Parts) GM-925 — — — — — — 50 — (Parts) GA-5410 — — — — — — — 50 (Parts) Characteristics Fineness of  62  64 65 68 63 63 66 62 monofilament Spinning property  2  4  0  0  0  1  0  0 (number of times) Thermal shrinkage (%)  2  1  4  3  6  6  2  7 Gloss Good Fair Good Good Excellent Good Good Good

TABLE 2 Comparative Examples 1 2 3 Blend TH-1000 100 100 100 (Parts) HA-24K — 10 50 (Parts) Characteristics Fineness of 68 68 70 monofilament Spinning 0 2 At least property 10 (number of times) Thermal At least At least At least shrinkage (%) 50 50 50 Gloss Excellent Good No good

In Table 1, “Spinning property” shows processability of a resin composition when it is subjected to melt spinning. In the test for the spinning property, a number of breaking of the fibers (a phenomenon such that some fibers break during melt extrusion, measuring time: 30 minutes and number of measurements: 3 times) was counted when 120 fibers were simultaneously extruded from a spinneret.

In Table 1, “Thermal shrinkage (%)” shows a ratio of thermal shrinkage when a specimen was thermally treated. Specifically, it is obtained in such a manner that 12 specimens of fibers each adjusted to a length of 100 mm, were left in a gear oven at 130° C. for 15 minutes, and a ratio in length of each specimen before and after being left, was calculated by ((length before being left−length after being left)/length before being left)×100. Further, a numerical value is an average value of 10 specimens after eliminating the maximum and the minimun among 12 of them.

In Table 1, “Gloss” is evaluated by visual determination of 24,000 bundled fibers inside a room which receives direct sunlight and under fluorescent light. The evaluation standards are the following.

Excellent: The fibers having smoothness and a little gloss Good: The fibers having a little smoothness and a little gloss Fair: The fibers having roughness and a little gloss, or having smoothness and a little gloss No good: The fibers having large roughness or too much gloss

From Tables 1 and 2, it is apparent that according to the present invention, it is possible to easily obtain a fiber which is excellent in the property of thermal shrinkage, has a little gloss and breaks less during melt-spinning.

INDUSTRIAL APPLICABILITY

The fiber obtained by using the resin composition of the present invention is useful for clothing fiber products such as underwears or socks, or household fiber products such as rugs, curtains or towels, particularly fibers for hair decorations or artificial hair.

The entire disclosure of Japanese Patent Application No. 2006-051859 filed on Feb. 28, 2006 including specification, claims and summary is incorporated herein by reference in its entirety. 

1. A vinyl chloride resin fiber made of a melt-spun fiber of a resin composition comprising a vinyl chloride resin and a polyester resin in an amount of from 1 to 300 parts by mass, based on 100 parts by mass of the vinyl chloride resin.
 2. The vinyl chloride resin fiber according to claim 1, wherein the vinyl chloride resin has a viscosity average polymerization degree of from 600 to 2,500.
 3. The vinyl chloride resin fiber according to claim 1, wherein the polyester resin has a melting point of from 100 to 300° C.
 4. The vinyl chloride resin fiber according to claim 1, wherein the polyester resin is a polylactic acid type resin.
 5. The vinyl chloride resin fiber according to claim 1, which has a fineness of monofilament of from 1 to 200 decitex.
 6. Artificial hair made of the vinyl chloride resin fiber as defined in claim
 1. 7. A process for producing a vinyl chloride resin fiber comprising the sequential steps: (a) mixing a resin composition comprising a vinyl chloride resin and a polyester resin; (b) melt-spinning the mixed resin composition from a spinneret at a resin temperature of from 150 to 200° C.; (c) stretching the melt-spun fiber in an atmosphere of air held at a temperature of from 30 to 150° C. to have a stretching ratio of from 2 to 20 times as much; and (d) subjecting the stretched fiber to a thermal relaxing treatment in an atmosphere of air held at a temperature of from 80 to 200° C. until the entire length of the fiber becomes from 99.8 to 50% of the length before the treatment.
 8. The process for producing a vinyl chloride resin fiber according to claim 7, wherein the sectional area per nozzle hole used in the melt-spinning step is at most 3 mm². 